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81.
82.
The sulfidation behavior of Fe-Nb alloys containing up to 30 w/o Nb was studied over the range of 600–900°C in 0.01 aim. S2 vapor. All alloys were two-phase, consisting of an Fe-rich solid solution and Fe2Nb, and followed the parabolic rate law at all temperatures. Scales consisted of two layers-an outer layer of FeS and an inner, complex layer which contained some FeS, FeNb2S4 (possibly some FeNb3S6), NbS2, and intermetallic particles which were either completely or only partially sulfidized. Platinum markers were located always at the interface between the two layers, which corresponded to the original metal surface. Activation energies were 18±3 kcal/mol in close agreement with the 19.8 reported for pure iron. The sulfidation rate decreased markedly with increasing Nb content of the alloys. The decrease is attributed to increasing amounts of Fe2Nb with increasing Nb, the net effect being that the diffusion path for outward iron diffusion through the inner layer is reduced as the Nb content increases. An analysis of the structure of NbS2 reveals that it is easily intercalated with Fe between loosely bonded layers of S-Nb-S. The S-Nb-S layers are covalently bonded which results in very low diffusivities of either S or Nb in pure NbS2. Although intercalated Fe tends to change the Van der Waal's type bonding between layers to more ionic or covalent, Fe diffuses readily between the layers in NbS2. Intercalation of Fe also increases the concentration of sulfur defects in NbS2, which in turn increases the diffusivity of sulfur. Nb was observed to be immobile. Thus, it is thought that either outward iron diffusion or inward sulfur diffusion in the inner layer is the rate-controlling step, in spite of the close agreement of activation energies with that of the sulfidation of pure iron. 相似文献
83.
84.
Graham M. Carter John L. Henshall Robert M. Hooper 《Journal of the American Ceramic Society》1988,71(5):270-C
Indentation creep of yttria- and calcia-fully-stabilized single-crystal zirconia has been observed at room temperature. The Knoop hardnesses decreased by 15% and 12% of their conventional short-time values, respectively, for indentation times of 100000 s. 相似文献
85.
The proton magnetic resonance spectra of isomeric triglycerides of isovaleric and palmitic acids in the presence of the downfield
and upfield chemical shift reagents Eu(fod)3 and Pr(fod)3 were studied. The resonance profiles of the γ-protons on the isovaleroyl chains are distinctive for each of the four possible
triglyceride isomers at low shift reagent/triglyceride ratios. With either reagent, the well defined γ-methyl isovalerate
doublets can be used to identify 2-isovaleroyl and 1,3-isovaleroyl structures and to analyze isomeric mixtures. This technique
will be useful for positional analysis of natural cetacean triglycerides containing isovaleric acid. 相似文献
86.
The jaw fat of the Atlantic bottlenose dolphin (Tursiops truncatus) contains unusual wax esters which can be separated into short chain (<C24) and long chain (>C24) fractions by thin layer chromatography. The short chain wax esters (28 wt. %) have been characterized as a 72∶24∶4 mixture
of isovaleroyl, isobutoryl, and 2-methylbutyrol, esters of C14–C18 n- and iso-alcohols. The intact <C24 esters have been resolved into individual molecular species by gas liquid chromatography on open-tubular polyester columns.
The long chain wax esters (12 wt. %) contain C10–C22 n- and iso-acids esterified to the same C14–C18 n- and iso-alcohols. Gas liquid chromatography of the intact, hydrogenated >C24 esters on a short JXR column has characterized them according to carbon number and the number of methyl branches they contain. 相似文献
87.
Continuous α-Fe2 O3 films grown on bulk (0001)Al2 O2 substrates by low-pressure chemical vapor deposition have been studied by transmission electron microscopy and the observations compared to those obtained from discontinuous films at an earlier stage of the growth process. Plan-view specimens revealed significant thermal stress in the continuous films, while cross-sectional specimens showed that cracking occurs in thicker films. The free surface of the film and the film/substrate interface appeared sharp and flat, apart from growth ledges and steps. Weak-beam imaging revealed a hexagonal misfit dislocation network consisting of perfect edge dislocations. Fine structure in the selected-area diffraction patterns which corroborates these observations is also discussed. The misfit network of partial dislocations previously observed in the discontinuous films was not observed for the continuous films, indicating an effect of film thickness, growth rate, or surface preparation on the Fe2 O3 /(0001)Al2 O3 interface structure. 相似文献
88.
Fairie Lyn Carter Vidabelle O. Cirino Layton E. Allen 《Journal of the American Oil Chemists' Society》1961,38(3):148-150
Except for a variation in the freeepsilon-amino lysine content of the protein, the Mexican screw-pressed meals were quite similar in their composition. The lysine
values for sesame protein obtained for the solvent-extracted meals were much higher than those obtained for the screw-pressed
meals. Screening of the endosperm and spermoderm from the solvent-extracted meals was effective in reducing the oxalate content
of the resulting flour although some epiderm fragments passed through a 60-mesh screen. The decortication process completely
removed the portion containing the oxalate from the seed and also reduced the calcium, sugar, and silica contents.
Presented at the annual meeting, American Oil Chemists' Society, Dallas, Tex., April 4–6, 1960.
One of the laboratories of the Southern Utilization Research and Development Division, Agricultural Research Service, U.S.
Department of Agriculture. 相似文献
89.
Hualong Li Emilie Hsu Jerzy Szpunar Ravi Verma Jon. T. Carter 《Journal of Materials Engineering and Performance》2007,16(3):321-326
In order to determine the deformation modes in AZ31 magnesium alloy at room temperature, computer simulations of deformation
texture development and calculation of formability have been carried out. The simulation results were compared with the measured
texture results. Based on agreement between the experiments and simulations the active deformation modes were determined.
A Visco Plastic Self Consistent model was employed for the simulation of plastic deformation. Simulations and experiments
were performed for different initial textures. The goal of the study was to develop the understanding of deformation texture
evolution and its effects on mechanical properties of magnesium, with an ultimate goal of improving room temperature formability
of magnesium alloys.
This article was presented at Materials Science & Technology 2006, Innovations in Metal Forming symposium held in Cincinnati,
OH, October 15-19, 2006. 相似文献
90.
Multilingual posts can potentially affect the outcomes of content analysis on microblog platforms. To this end, language identification can provide a monolingual set of content for analysis. We find the unedited and idiomatic language of microblogs to be challenging for state-of-the-art language identification methods. To account for this, we identify five microblog characteristics that can help in language identification: the language profile of the blogger (blogger), the content of an attached hyperlink (link), the language profile of other users mentioned (mention) in the post, the language profile of a tag (tag), and the language of the original post (conversation), if the post we examine is a reply. Further, we present methods that combine these priors in a post-dependent and post-independent way. We present test results on 1,000 posts from five languages (Dutch, English, French, German, and Spanish), which show that our priors improve accuracy by 5 % over a domain specific baseline, and show that post-dependent combination of the priors achieves the best performance. When suitable training data does not exist, our methods still outperform a domain unspecific baseline. We conclude with an examination of the language distribution of a million tweets, along with temporal analysis, the usage of twitter features across languages, and a correlation study between classifications made and geo-location and language metadata fields. 相似文献